Method and apparatus for power control in a wireless communication system

ABSTRACT

Method and Apparatus for performing power control on the power control commands transmitted on a forward link in a wireless communication system. The power level of the power control bits on the forward link are adjusted in response to power commands received on the reverse link. The mobile station measures the power level of the adjusted power control bits to measure the quality of the forward link.

BACKGROUND

[0001] 1. Field

[0002] The present invention relates generally to communication, andmore specifically to power control in a wireless communication system.

[0003] 2. Background

[0004] Increasing demand for wireless data transmission and theexpansion of services available via wireless communication technologyhave led to the development of systems capable of handling voice anddata services. One spread spectrum system designed to handle the variousrequirements of these two services is a Code Division Multiple Access,CDMA, system referred to as cdma2000, which is specified in“TIA/EIA/IS-2000 Standards for CDMA2000 Spread Spectrum Systems.”

[0005] As the amount of data transmitted and the number of transmissionsincrease, the limited bandwidth available for radio transmissionsbecomes a critical resource. There is a need, therefore, for anefficient and accurate method of transmitting information in acommunication system that optimizes use of available bandwidth.

SUMMARY

[0006] Embodiments disclosed herein address the above stated needs by aremote station apparatus having a link quality estimation unit operativeto generate a link quality estimate in response to a first power controlinstruction received on a common channel, and a power control unitcoupled to the link quality estimation unit, the power control unitoperative to generate a second power control instruction in response tothe link quality estimate.

[0007] According to an alternate aspect, a base station apparatusincludes a decoder, and a determination unit coupled to the decoder, thedetermination operative to determine a power control instruction forbase station transmission on a common channel, and an adjustment unitcoupled to the determination unit, the adjustment unit operative toadjust a power level of the power control instruction.

[0008] According to still another aspect, a base station apparatusincludes a control processor for power control of transmission of powercontrol instructions on a common channel, and an amplifier operative toadjust a power level of the power control instructions.

[0009] In one aspect, a wireless communication system includes a firstpower control unit operative to transmit reverse link power controlinstructions on a common channel, and a second power control unitoperative to adjust transmission power of the reverse link power controlinstructions in response to forward link power control instructionsreceived on a reverse link.

[0010] In another aspect, a method for power control in a wirelessapparatus operative in a communication system having a forward link anda reverse link, the system transmitting power control bits on a forwardlink common channel, includes measuring a SNR of at least one powercontrol bit for controlling a reverse link, and determining a powercontrol decision for the forward link based on the SNR.

[0011] In still another aspect, a method for power control in a wirelesscommunication system, the system having a forward link and a reverselink, the system transmitting power control instructions on a forwardlink common channel, includes determining a first power controlinstruction for control of the reverse link, in response to receiving asecond power control instruction on the reverse link, the second powercontrol instruction for control of the forward link, determining a firsttransmission power level, and transmitting the first power controlinstruction at the first transmission power level on the common channel.

[0012] In yet another aspect, a method for power control in a wirelesscommunication system, the system having a forward link and a reverselink, the system transmitting power control instructions on a forwardlink common channel, includes generating a reverse link power controlinstruction, generating a forward link power control instruction, andadjusting a power level for transmission of the forward link powercontrol instruction according to the reverse link power controlinstruction.

BRIEF DESCRIPTION OF THE DRAWINGS

[0013]FIG. 1 is a diagram of a communication system having a wiredsubsystem and a wireless subsystem;

[0014]FIG. 2 is a diagram of an architectural model of a Reverse Linkchannel is a communication system;

[0015]FIG. 3 is diagram of an architectural model of a logical channelin a communication system;

[0016]FIG. 4 is a timing diagram of power control on a dedicated channelin a communication system;

[0017]FIG. 5 is a timing diagram of power control on a shared controlchannel in a communication system;

[0018]FIG. 6 is a flow diagram of a method of power control in acommunication system;

[0019]FIG. 7 is a timing diagram of power control of power control bitson a shared control channel in a communication system;

[0020]FIG. 8 is a diagram of a wireless apparatus compatible with acommunication system protocol performing power control on a commonchannel of the forward link; and

[0021]FIG. 9 is a diagram of a base station apparatus compatible with acommunication system performing power control on a common channel of theforward link.

DETAILED DESCRIPTION

[0022] The word “exemplary” is used exclusively herein to mean “servingas an example, instance, or illustration.” Any embodiment describedherein as “exemplary” is not necessarily to be construed as preferred oradvantageous over other embodiments.

[0023] In a spread-spectrum wireless communication system, such as acdma2000 system, multiple users transmit to a transceiver, often a basestation, in the same bandwidth at the same time. The base station may beany data device that communicates through a wireless channel or througha wired channel, for example using fiber optic or coaxial cables. A usermay be any of a variety of devices including but not limited to a PCcard, a compact flash, an external or internal modem, or a wireless or awireline phone. A user is also referred to as a remote station. Thecommunication link through which the user transmits signals to thetransceiver is called a Reverse Link, RL. The communication link throughwhich a transceiver sends signals to a user is called a Forward Link,FL. As each user transmits to and receives from the base station, otherusers are concurrently communicating with the base station. Each user'stransmissions on the FL and/or the RL introduces interference to otherusers. To overcome interference in the received signals, a demodulatorseeks to maintain a sufficient ratio of bit energy to interference powerspectral density, E_(b)/N₀, in order to demodulate the signal at anacceptable probability of error. Power Control, PC, is a process thatadjusts the transmitter power of one or both of the Forward Link, FL,and the Reverse Link, RL, to satisfy a given error criteria. Ideally,the power control process adjusts the transmitter power(s) to achieve atleast the minimum required E_(b)/N₀ at the designated receiver. Stillfurther, it is desirable that no transmitter uses more than the minimumE_(b)/N₀. This ensures that any benefit to one user achieved through thepower control process is not at the unnecessary expense of any otheruser.

[0024] For clarity PC information sent via the FL will be referred to as“FL PC commands” and PC information sent via the RL will be referred toas “RL PC commands.” The FL PC commands provide PC information forcontrol of the RL transmit power. The RL PC commands provide PCinformation for control of the FL transmit power.

[0025] In a spread-spectrum system, such as a CDMA system, performanceof the system is interference-limited. The capacity of the system andthe quality of the system are, therefore, limited by the amount ofinterference power present in a transmission. Capacity is defined as thetotal number of simultaneous users the system can support, and qualityas the condition of the communication link as perceived by the receiver.Power control impacts the capacity of the system by ensuring that eachtransmitter only introduces a minimal amount of interference to otherusers and thus increases “processing gain.” Processing gain is the ratioof the transmission bandwidth, W, to the data rate, R. A quality measureof the transmission link may be defined as the ratio of E_(b)/N₀ to W/R,corresponding to the Signal-to-Noise Ratio, SNR. Processing gainovercomes a finite amount of interference from other users, i.e., totalnoise. System capacity is, therefore, proportional to processing gainand SNR.

[0026]FIG. 1 illustrates a wireless communication system 20, wherein inone embodiment system 20 is a cdma2000 system. System 20 includes twosegments: a wired subsystem and a wireless subsystem. The wiredsubsystem is the Public Switched Telephone Network, PSTN 26, and theInternet 22. The Internet 22 portion of the wired subsystem interfaceswith the wireless subsystem via Inter-Working Function Internet, IWF 24.The ever-increasing demand for data communications is typicallyassociated with the Internet and the ease of access to the dataavailable thereby. However, advancing video and audio applicationsincrease the demand for transmission bandwidth.

[0027] The wired subsystem may include but is not limited to othermodules such as an instrumentation unit, a video unit, etc. The wirelesssubsystem includes the base station subsystem, which involves the MobileSwitching Center, MSC 28, the Base Station Controller, BSC 30, the BaseTransceiver Station(s), BTS(s) 32, 34, and the Mobile Station(s), MS(s)36, 38. The MSC 28 is the interface between the wireless subsystem andthe wired subsystem. It is a switch that talks to a variety of wirelessapparatus. The BSC 30 is the control and management system for one ormore BTS(s) 32, 34. The BSC 30 exchanges messages with the BTS(s) 32, 34and the MSC 28. Each of the BTS(s) 32, 34 consist of one or moretransceivers placed at a single location. Each of the BTS(s) 32, 34terminates the radio path on the network side. The BTS(s) 32, 34 may bein co-located with BSC 30 or may be independently located.

[0028] The system 20 includes radio air interface physical channels 40,42 between the BTS(s) 32, 34 and the MS(s) 36, 38. The physical channels40, 42 are communication paths described in terms of the digital codingand RF characteristics. According to one embodiment, in addition to thephysical channels 40, 42, the system 20 incorporates logical channels,such as that illustrated in FIG. 2. Each logical channel is acommunication path within the protocol layers of either the BTS(s) 32,34 or the MS(s) 36, 38. Information is grouped onto a logical channelbased upon criteria such as the number of users, the transmission type,the direction of the transfer, etc. The information on a logical channelis ultimately carried on one or more physical channels. Mappings aredefined between logical and physical channels. These mappings may bepermanent or may be defined only for the duration of a givencommunication. In the exemplary logical channel of FIG. 2, a forwardcommon signaling channel, F-CSCH 50, carries information that may bemapped to the Forward Sync Channel, F-SYNCH 52, the Forward PagingChannel, F-PCH 54, and the Forward Broadcast Control Channel, F-BCCH 56.

[0029] As discussed hereinabove, a FL is defined as a communication linkfor transmissions from one of the BTS(s) 32, 34 to one of the MS(s) 36,38. An RL is defined as a communication link for transmissions from oneof the MS(s) 36, 38 to one of the BTS(s) 32, 34. According to oneembodiment, power control within system 20 includes controlling transmitpower for both the RL and the FL. Multiple power control mechanisms maybe applied to the FL and RL in system 20, including reverse open looppower control, reverse closed loop power control, forward closed looppower control, etc. Reverse open loop power control adjusts the initialaccess channel transmission power of MS(s) 36, 38, and compensates forvariations in path loss attenuation of the RL. The RL uses two types ofcode channels: traffic channel(s), and access channel(s). FL and RLtraffic channels typically include a Fundamental Code Channel, FCCH, andmultiple Supplemental Code Channels, SCCHs. The FCCH serves as theprimary channel for all traffic communications in the FL and RL. In oneembodiment, each FCCH is associated with an instance of a spreadingcode, such as a Walsh code. RL Access Channel(s), RACH(s), are eachassociated with a Paging Channel, PCH. FIG. 3 illustrates an RL channelarchitecture according to one embodiment.

[0030] According to one embodiment, within system 20, closed loop powercontrol compensates for fading environments of both the FL and RL.During closed loop power control, the receiver measures the incomingE_(b)/N₀ and provides feedback to the transmitter instructing either anincrease or decrease in transmit power. In one embodiment the change ismade in 1dB steps. Alternate embodiments may employ alternate values ofa constant value step, or may implement dynamic step size values, e.g.,as a function of power control history. Still other embodiments may varythe step size based on performance and/or requirements of the system 20.Power control of the RL is performed by the BTS(s) 32, 34, wherein ameasurement is made of received signals and compared to a threshold. Adecision is then made as to whether the power received is above or belowthreshold. The decision is transmitted as FL PC command to a given user,such as MS(s) 36, 38, respectively. In response to the command, the RLtransmit power is adjusted. During closed loop power control of the RL,FL PC commands may be punctured into the FL transmission periodically toprovide the feedback to the MS(s) 36, 38. Puncturing replacestransmission signals with FL PC commands. The puncturing may be donewithin each frame, wherein a transmission is broken into frames of agiven time duration.

[0031] The system 20 is designed for transmission of voice information,data information, and/or both voice and data. FIG. 4 illustrates aFundamental Channel, FCH, for voice-containing communications. Thesignal strength of the FCH is illustrated as a function of time. A firstframe is illustrated from time t₀ to time t₃. Subsequent frames areillustrated from time t₃ to t₆, and t₆ to t₉, respectively. The firstframe includes a FL PC command that was punctured in from time t₁ to t₂.The punctured PC bit replaces information transmitted during that time.Similarly, PC bits are punctured into the subsequent frame from t₄ tot₅, and the next frame from t₇ to t₈. Note that a power controlinstruction may be completed over multiple frames. In one embodiment,the FL PC commands are placed in a pseudo-random manner. In alternateembodiments, the FL PC commands may be placed in fixed time slots orrelative time slots.

[0032] For power control of the FL, RL PC commands are provided to theBTS(s) 32, 34 from the MS(s), 36, 38, respectively. Closed loop powercontrol of the FL counts the number of bad frames received during agiven period and sends a report to the BTS(s) 32, 34. The message may besent periodically, or when the error rate reaches a threshold, whereinthe threshold is set by the system 20. In one embodiment, each frametransmitted by the MS(s) 36, 38 contains an Erasure Indicator Bit (EIB)that is set to indicate an erasure. The FL power is adjusted based onthe EIB history.

[0033] Closed loop power control consists of two feedback loops: aninner loop and an outer loop. The outer loop measures the frame errorrate and periodically adjusts a setpoint up or down to maintain thetarget frame error rate. If the frame error rate is too high, thesetpoint is increased and if the frame error rate is too low, thesetpoint is decreased. The inner loop measures the received signal leveland compares it to the setpoint. Power control commands are then sent toincrease or decrease power as needed to keep the received signal levelclose to the setpoint. The two loops operate in concert to ensuresufficient signal strength to demodulate the signal at an acceptableprobability of error and to minimize the interference to other users.

[0034] The FL includes Common Channels, including but not limited to thePilot Channel(s), the Common Control Channel, CCH, the BroadcastChannel, BCH, and the Common Power Control Channel, CPCCH. The CCHcarries mobile directed messages for compatible mobiles. The BCH carriesbroadcast messages for compatible mobiles, including overhead messages.The CPCCH is used to send Power Control, PC, bits to the mobile so thatACH messages may be sent under power control.

[0035] Most multiple access wireless communication systems, such asspread spectrum systems, capable of voice and data transmissions seek tooptimize the physical channel usage in order to serve high data rates tothe users. Such systems may employ a low rate channel, referred to as aFundamental Channel, FCH. The FCH is used for voice and signalingtransmissions. Each FCH is associated with multiple high rate channels,referred to as Supplemental Channels. The Supplemental Channels are usedfor data transmissions. While the FCH use little energy, each FCHrequires a dedicated Walsh code, resulting in a large aggregate energyover multiple FCH. For data communications the FCH are idle much of thetime. In this condition, the FCH waste Walsh codes and power that couldbe used to increase the capacity and performance of the system. To avoidthe waste, one embodiment assigns several FCH(s) to one or more commonchannels, shared by all users. The Walsh code usage, or Walsh space, isreduced to one Walsh code, and the power consumed by otherwise idleFCH(s) is reduced.

[0036] As power control instructions were previously transmitted on theindividually assigned FCH(s), the introduction of the shared commonchannels brought about the use of a Common Power Control Channel, CPCCH.The CPCCH is used for power control of the RL, wherein different usersshare the channel in a time division manner. FL PC commands are sent viathe CPCCH.

[0037]FIG. 5 illustrates the placement of FL PC commands for mobileusers labeled A and B. The FL PC commands are transmitted on the CPCCHand are plotted as a function of time. The FL PC commands aretransmitted at full power or a predetermined power level. The commandsfor the users A and B are time division multiplexed together on theCPCCH. The placement of the individual FL PC commands may be at a fixedtime or may be placed in another manner, such as a pseudo-random manner.

[0038] In the system 20 of FIG. 1 the FL PC commands may be transmittedvia the Common Power Control Channel, CPCCH, or on a dedicated channel,such as a FCH. The Forward Common Power Control Channel, F-CPCCH, isused to send FL PC commands to the MS(s) 36, 38 that are used to controlthe Reverse Common Control Channel, R-CCH. As discussed hereinabove,open loop power control is used on the Reverse Access Channel, R-ACH.Each MS(s) 36, 38 repeatedly transmits with increasing power until itreceives an acknowledgement from the BTS(s) 32, 34, respectively, oruntil the maximum number of probes and probe sequence is reached.

[0039] It is often desirable to continue power control of the FL, evenwhen no data is transmitted. For example, if only a few frames of dataare to be transmitted on the Supplemental Channel, updating powercontrol of the FL enhances the transmission of the Supplemental Channelallowing transmission with the required power and saving power.Additionally, for data transmissions, continuing the power control ofthe FL provides the data scheduler with information regarding thequality of the link at a given time. This information allows thescheduler to take advantage of the channel using a given schedulingscheme.

[0040] Further, it is desirable for the mobile station to ascertain theresponse of the base station to RL PC commands. Using a shared commonchannel, the mobile station may not see the effect of the RL PCcommands. For example, the mobile station may know the E_(b)/N₀ of theFL subsequent to a series of RL PC commands. The RL PC commands may havebeen corrupted at the base station receiver. Ideally, the FL includes apower indication that echoes the RL PC commands received at the basestation. Using the FCH, the mobile station was able to measure the FCHfor such feedback. In one embodiment using the shared common channel,the feedback is provided as a function of the power level of RL PCcommands.

[0041]FIG. 6 illustrates a method 100 for power control in system 20,wherein the FL PC commands controlling the RL are transmitted on theCPCCH of the FL. According to method 100, RL PC commands are used toadjust the power level of the FL PC commands. The method 100 initiallysets the FL PC command transmission power for the FL to a predeterminedreference power level at step 102. On receipt of a RL PC command fromthe MS a decision is made at step 104 as to whether an UP or DOWNinstruction was received. If an UP command was received, the FL PCcommand power level is incremented at step 106. The increment may be astep value or a function of the previously transmitted power controlbit(s) transmitted on the FL. If the RL PC command received was a DOWNinstruction, the FL PC command power level FL is decremented at step108. The decrement may be a step value or a function of the previouslytransmitted power control bit(s) transmitted on the FL or may be afunction of commands received. Subsequent to step 108 or step 106,processing continues to transmit the next FL PC command at the adjustedpower level at step 110. If a RL PC command is received at step 112,processing then returns to step 104 to determine the instruction. Themethod 100 effectively performs FL power control of the FL PC commands.Note that the FL PC command information is not impaired by the powercontrol of method 100. The FL PC command information is used for powercontrol of the RL.

[0042] When the base station adjusts the power level of the FL PCcommand in response to RL PC command, such as according to the method110 of FIG. 6, the mobile station may use the power level of the FL PCcommand to make power control decisions estimating the quality of theFL. The mobile station may then use this information to generate powercontrol commands. According to one embodiment, the mobile stationmeasures the SNR of the FL PC bits on the CPCCH. The SNR is thencompared to a threshold value. A corresponding power control command istransmitted in response to the comparison. The FL is prepared totransmit at the correct power level, and the base station may use thetransmitted power as an indication of channel quality. According to oneembodiment, the RL PC command is included in a Data Rate Channel, DRCtransmission.

[0043]FIG. 7 illustrates a timing scenario implementing the method 100of FIG. 6. The RL PC command transmissions and the FL PC commandtransmissions are illustrated as a function of time. A first FL PCcommand is transmitted from time t₁ to t₂ at a first power level A.Subsequent to the first FL PC command, an RL PC command is transmittedfrom time t₃ to t₄. The RL PC command corresponds to a DOWN command. Inresponse to the DOWN command, the base station decrements the powerlevel of the next transmitted FL PC command. As illustrated, the next FLPC command is transmitted from time t₅ to t₆ at an adjusted power levelB.

[0044] Continuing with FIG. 7, at time t₇ an RL PC command indicates anUP command. In response to the UP command, the base station incrementsthe power level of the next transmitted FL PC command. As illustratedthe power level of the FL PC command transmitted from time t₉ to t₁₀ isreturned to level A.

[0045] The method 100 is applicable to a variety of systems andscenarios. For example, the method 100 may be applied to datatransmissions in which the base station receives more data from mobilestations than is transmitted on the FL. In one embodiment, a wirelessbanking system incorporates the method 100 of FIG. 6. A centralprocessing center, similar to the BTS(s) 32, 34 receives informationregarding a bank transaction or credit purchase via the RL. Most of thetransmissions are performed on the RL; therefore, power control istypically performed on the RL exclusively. In this scenario, powercontrol is implemented on the FL as well and serves to enhance the RLpower control. In an alternate embodiment, the method 110 is applied toa distributed meter reporting system, such as a utility meter reportingsystem. In this case, the central processing center receives informationfrom multiple units or meters.

[0046]FIG. 8 illustrates an embodiment of a wireless apparatus 200, suchas a remote station or a mobile station, compatible with a spreadspectrum system implementing a common channel on the FL that transmitspower control decisions for the RL, such as a CDMA2000 system. Thewireless apparatus 200 is an integral part of power control for both theRL and the FL. As illustrates, the FL PC commands are transmitted viathe CPCCH. In alternate embodiments the FL PC commands may betransmitted via an alternate control channel. The FL PC commands provideinformation containing instructions for power control of the RL. The FLPC commands have been power controlled to reflect the instructionstransmitted by the wireless apparatus 200 to a base station (not shown)as RL PC commands for control of the FL. In this way, the RL PC commandseffectively perform power control of the FL PC commands. The wirelessapparatus 200 receives the FL PC commands, as well as other informationvia the CPCCH at receive circuitry 202. The receive circuitry 202 mayinclude but is not limited to an antenna or multiple antennas, apreprocessing unit for multiple access communications, a frequencydespread unit, and a demodulator.

[0047] The receive circuitry 202 is coupled to SNR estimator 204operative to estimate the E_(b)/N₀ of the received signals. The SNRestimator 204 generates an estimate of E_(b)/N₀ and provides theestimate to a threshold comparator 206. The threshold comparator 206compares the E_(b)/N₀ estimate to a predetermined or precalculatedthreshold value, referred to as a setpoint. The setpoint is monitoredand updated by a setpoint adjustment unit 212 coupled to the thresholdcomparator 206. As discussed hereinabove, the setpoint adjustment is apart of the outer loop of power control and is a function of the frameerror rate. There are many decision criteria and methods for performingthe operation of setpoint adjustment unit 212. The result of thecomparison of threshold comparator 206 is provided to PC bit decisionunit 208 to determine a next power control instruction to send to thebase station. By determining the quality of the FL by way of the FL PCbits received on the CPCCH, the wireless apparatus 200 is able toprovide accurate power control instructions to the base station.

[0048] The PC bit decision is then provided to generation unit 210 togenerate the RL PC bit, or RL PC message, for transmission on the RL.The generation unit 210 is coupled to amplifier 214, which receives theRL PC bit from generation unit 210. The amplifier 214 transmits the RLPC bit and to transmit circuitry 216. The amplification level isprovided by power control of the RL as a result of instructions from thebase station. The signal information is provided from the receivecircuitry 202 to a decoder 218 for extraction of the power controlinstruction for the RL. The decoder 218 decodes the information receivedon the CPCCH and determines the corresponding FL PC command. The FL PCcommand is then provided to an adjustment unit 222 that adjusts thetransmit power of the RL. The adjustment is provided as a control inputto amplifier 214, which applies the appropriate amplification factor todata and control information for transmission on the RL. The amplifier214 also applies the power control to RL PC commands for transmission.

[0049] One embodiment of a base station 300 compatible with the wirelessapparatus 200 is illustrated in FIG. 9. At the base station 300, RL PCbits are received via the RL at receive circuitry 302. The receivecircuitry 302 may include but is not limited to an antenna or multipleantennas, a preprocessing unit for multiple access communications, afrequency despread unit, and a demodulator. The receive circuitry 302 iscoupled to a decoder 304 that extracts the RL PC command from thereceived signal. The command is then provided to an adjustment unit 308to adjust the FL traffic transmit power. The adjustment is provided ascontrol information to amplifier 312. The PC command from decoder 304 isalso provided to a PC adjustment unit 310. The adjustment unit 310adjusts the transmit power level of the PC bits for transmission in theCPCCH according to the RL PC command. The amplifier 312 applies theappropriate amplification factor to data and/or control information fortransmission by base station 300 as well as to FL PC commands. Note thatbase station 300 determines the power control instructions fortransmission to the wireless apparatus 200, wherein the power controlinstructions are PC bits transmitted on the CPCCH. A variety of powercontrol decision mechanisms may be implemented to determine theappropriate power control instructions to control the RL.

[0050] Those of skill in the art would understand that information andsignals may be represented using any of a variety of differenttechnologies and techniques. For example, data, instructions, commands,information, signals, bits, symbols, and chips that may be referencedthroughout the above description may be represented by voltages,currents, electromagnetic waves, magnetic fields or particles, opticalfields or particles, or any combination thereof.

[0051] Those of skill would further appreciate that the variousillustrative logical blocks, modules, circuits, and algorithm stepsdescribed in connection with the embodiments disclosed herein may beimplemented as electronic hardware, computer software, or combinationsof both. To clearly illustrate this interchangeability of hardware andsoftware, various illustrative components, blocks, modules, circuits,and steps have been described above generally in terms of theirfunctionality. Whether such functionality is implemented as hardware orsoftware depends upon the particular application and design constraintsimposed on the overall system. Skilled artisans may implement thedescribed functionality in varying ways for each particular application,but such implementation decisions should not be interpreted as causing adeparture from the scope of the present invention.

[0052] The various illustrative logical blocks, modules, and circuitsdescribed in connection with the embodiments disclosed herein may beimplemented or performed with a general purpose processor, a digitalsignal processor (DSP), an application specific integrated circuit(ASIC), a field programmable gate array (FPGA) or other programmablelogic device, discrete gate or transistor logic, discrete hardwarecomponents, or any combination thereof designed to perform the functionsdescribed herein. A general-purpose processor may be a microprocessor,but in the alternative, the processor may be any conventional processor,controller, microcontroller, or state machine. A processor may also beimplemented as a combination of computing devices, e.g., a combinationof a DSP and a microprocessor, a plurality of microprocessors, one ormore microprocessors in conjunction with a DSP core, or any other suchconfiguration.

[0053] The steps of a method or algorithm described in connection withthe embodiments disclosed herein may be embodied directly in hardware,in a software module executed by a processor, or in a combination of thetwo. A software module may reside in RAM memory, flash memory, ROMmemory, EPROM memory, EEPROM memory, registers, hard disk, a removabledisk, a CD-ROM, or any other form of storage medium known in the art. Anexemplary storage medium is coupled to the processor such the processorcan read information from, and write information to, the storage medium.In the alternative, the storage medium may be integral to the processor.The processor and the storage medium may reside in an ASIC. The ASIC mayreside in a user terminal. In the alternative, the processor and thestorage medium may reside as discrete components in a user terminal.

[0054] The previous description of the disclosed embodiments is providedto enable any person skilled in the art to make or use the presentinvention. Various modifications to these embodiments will be readilyapparent to those skilled in the art, and the generic principles definedherein may be applied to other embodiments without departing from thespirit or scope of the invention. Thus, the present invention is notintended to be limited to the embodiments shown herein but is to beaccorded the widest scope consistent with the principles and novelfeatures disclosed herein.

What is claimed is:
 1. A remote station apparatus comprising: a linkquality estimation unit operative to generate a link quality estimate inresponse to a first power control instruction received on a commonchannel; and a power control unit coupled to the link quality estimationunit, the power control unit operative to generate a second powercontrol instruction in response to the link quality estimate.
 2. Theremote station apparatus of claim 1, wherein the remote stationapparatus controls transmission power in response to the first powercontrol instruction.
 3. The remote station apparatus of claim 1, whereinthe remote station apparatus transmits the second power controlinstruction.
 4. A base station apparatus comprising: a decoder; and adetermination unit coupled to the decoder, the determination operativeto determine a power control instruction for base station transmissionon a common channel; and an adjustment unit coupled to the determinationunit, the adjustment unit operative to adjust a power level of the powercontrol instruction.
 5. A base station apparatus comprising: a controlprocessor for power control of transmission of power controlinstructions on a common channel; and an amplifier operative to adjust apower level of the power control instructions.
 6. A wirelesscommunication system comprising: a first power control unit operative totransmit reverse link power control instructions on a common channel;and a second power control unit operative to adjust transmission powerof the reverse link power control instructions in response to forwardlink power control instructions received on a reverse link.
 7. A methodfor power control in a wireless apparatus operative in a communicationsystem having a forward link and a reverse link, the system transmittingpower control bits on a forward link common channel, the methodcomprising: measuring a SNR of at least one power control bit forcontrolling a reverse link; and determining a power control decision forthe forward link based on the SNR.
 8. A method for power control in awireless communication system, the system having a forward link and areverse link, the system transmitting power control instructions on aforward link common channel, the method comprising: determining a firstpower control instruction for control of the reverse link; in responseto receiving a second power control instruction on the reverse link, thesecond power control instruction for control of the forward link,determining a first transmission power level; and transmitting the firstpower control instruction at the first transmission power level on thecommon channel.
 9. A method for power control in a wirelesscommunication system, the system having a forward link and a reverselink, the system transmitting power control instructions on a forwardlink common channel, the method comprising: generating a reverse linkpower control instruction; generating a forward link power controlinstruction; and adjusting a power level for transmission of the forwardlink power control instruction according to the reverse link powercontrol instruction.